RAN-Controlled Selective Handover Between First and Second RAN:S

ABSTRACT

The present disclosure relates to a method, in a mobility function (MF) node. The method comprises receiving (S1) information about a mapping to a property, of each of a plurality of radio bearers of a radio device for carrying data traffic between the radio device and a first radio access network (RAN). The method also comprises determining (S2) based on the received (S1) information, that at least one of the radio bearers can be handed over to a second RAN. The method also comprises initiating (S3) a handover command to the radio device instructing the radio device to hand over the at least one radio bearer to the second RAN.

TECHNICAL FIELD

The present disclosure relates generally to wireless devices thatsupport multiple radio access technologies (RATs) and more particularlyrelates to the handing over of data traffic from one radio accessnetwork (RAN) to another with such a device.

BACKGROUND

The wireless local-area network (WLAN) technology known as “Wi-Fi” hasbeen standardized by IEEE in the 802.11 series of specifications (i.e.,as “IEEE Standard for Information technology—Telecommunications andinformation exchange between systems. Local and metropolitan areanetworks—Specific requirements. Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications”). As currentlyspecified, Wi-Fi systems are primarily operated in the 2.4 GHz or 5 GHzbands.

The IEEE 802.11 specifications regulate the functions and operations ofthe wireless access points (AP) or wireless terminals, collectivelyknown as “stations” or “STA,” in the IEEE 802.11 specification,including the physical layer protocols, Medium Access Control (MAC)layer protocols, and other aspects needed to secure compatibility andinter-operability between access points and portable terminals. BecauseWi-Fi is generally operated in unlicensed bands, communication overWi-Fi may be subject to interference sources from any number of bothknown and unknown devices. Wi-Fi is commonly used as wireless extensionsto fixed broadband access, e.g., in domestic environments and inso-called hotspots, like airports, train stations and restaurants.

Recently, Wi-Fi has been subject to increased interest from cellularnetwork operators, who are studying the possibility of using Wi-Fi forpurposes beyond its conventional role as an extension to fixed broadbandaccess. These operators are responding to the ever-increasing marketdemands for wireless bandwidth, and are interested in using Wi-Fitechnology as an extension of, or alternative to, cellular radio accessnetwork technologies. Cellular operators that are currently servingmobile users with, for example, any of the technologies standardized bythe 3rd-Generation Partnership Project (3GPP), including theradio-access technologies known as Long-Term Evolution (LTE), UniversalMobile Telecommunications System/Wideband Code-Division Multiple Access(UMTS/WCDMA), and Global System for Mobile Communications (GSM), seeWi-Fi as a wireless technology that can provide good additional supportfor users in their regular cellular networks.

As used herein, the term “operator-controlled Wi-Fi” indicates a Wi-Fideployment that on some level is integrated with a cellular networkoperator's existing network, where the operator's RAN(s) and one or moreWi-Fi wireless access points may even be connected to the same corenetwork (CN) and provide the same or overlapping services. Currently,several standardization organizations are intensely active in the areaof operator-controlled Wi-Fi. In 3GPP, for example, activities toconnect Wi-Fi access points to the 3GPP-specified core network are beingpursued. In the Wi-Fi alliance (WFA), activities related tocertification of Wi-Fi products are undertaken, which to some extent arealso driven from the need to make Wi-Fi a viable wireless technology forcellular operators to support high bandwidth offerings in theirnetworks. In these standardization efforts, the term “Wi-Fi offload” iscommonly used and indicates that cellular network operators seek meansto offload traffic from their cellular networks to Wi-Fi, e.g., duringpeak-traffic-hours and in situations when the cellular network needs tobe off-loaded for one reason or another, e.g., to provide a requestedquality-of-service, to maximize bandwidth, or simply for improvedcoverage.

For a wireless operator, offering a mix of two technologies that havebeen standardized in isolation from each other raises the challenge ofproviding intelligent mechanisms for co-existence. One area that needsthese intelligent mechanisms is connection management.

Many of today's wireless devices (referred to hereinafter as “userequipment” (UE) or “radio device” or “mobile terminal”) support Wi-Fi inaddition to one or several 3GPP cellular technologies. In many cases,however, these terminals essentially behave as two separate devices,from a radio access perspective. The 3GPP radio access network and theUE-based modems and protocols that are operating pursuant to the 3GPPspecifications are generally unaware of the wireless access Wi-Fiprotocols and modems that may be simultaneously operating pursuant tothe 802.11 specifications. Techniques for coordinated control of thesemultiple radio-access technologies are needed.

In 3GPP radio access technologies, it is the network that decides whenthe mobile device shall handover from one cell to another cell. Thenetwork makes that decision based on radio measurement reports that thenetwork requests from the mobile device and potential other informationthat is available to the network. As noted above, a number of activitiesare ongoing to integrate WLAN with the 3GPP architecture. In the latestspecifications for 3GPP networks, 3GPP release 11 (Rel-11), thisintegration is still fairly “loose” and the decision when to handoverbetween 3GPP radio access and WLAN is left to the mobile device. Work isongoing now to change this by letting the network decide when tohandover between 3GPP and WLAN.

When the network decides such handover, it also needs to decide whatportion of this mobile device's traffic to handover. For example, sometraffic may stay at the source access, and some traffic may be moved tothe target access. Accordingly, improved techniques for deciding whichtraffic to handover are needed.

Fixed-Mobile Convergence (FMC) is a trend that has been on-going formany years now. The overall aim of FMC is to provide a seamless userexperience; i.e., a particular service can be used anywhere, at anytime. The user generally is not concerned with where the service islocated or via which access technology the service is reached at aparticular point in time. In the last few years, efforts on FMC havemainly focused on integration of WLAN (Wireless Local Area Network) with3GPP (3rd Generation Partnership Project) technologies. The vision is aheterogeneous network, where WLAN is integrated into the 3GPP EvolvedPacket Core (EPC) just like any other cellular radio-access technology(RAT).

One key driver for the integration of WLAN with 3GPP is the large growthin mobile broadband traffic. To accommodate this, the unlicensed WLANspectrum can serve as a complement to the 3GPP RAT spectrum. Anotherdriver is the wide support of WLAN in devices. Most modern mobiledevices include both 3GPP radio and WLAN radio. Yet another driver isthe desire from operators to support the same services regardlessaccess.

A 3GPP UE (User Equipment, the 3GPP terminology for a mobile device) canattach to a non-3GPP access network (e.g., a WLAN access network) andget connected to one or more PDNs (Packet Data Networks) via the S2interface. Each PDN connection is anchored in a 3GPP PGW (PDN Gateway).The UE receives one internet protocol (IP) address/prefix for each PDNconnection. It is the PGW that assigns the address/prefix.

The S2 interface comes in three versions: S2a, S2b and S2c. The lattertwo overlay the non-3GPP access network and do not impact it. S2a is amore converged solution that does impact the non-3GPP access.

The FIGS. 1 and 2 describe the concepts of PDN, APN, PGW, SGW, PDNconnection, EPS bearer, TWAG, AC and AP. See also 3GPP technicalspecification (TS) 23.402, “Architecture enhancements for non-3GPPaccesses”.

PDN is the packet data network, an IP network, typically Internet, butcan alternatively be e.g. an IP multimedia subsystem (IMS) servicenetwork.

PGW is the PDN gateway, a functional node providing access to one ormore PDNs.

A PDN connection provides the UE with an access channel to a PDN. It isa logical tunnel between the UE and the PGW. Each PDN connection has asingle IP address/prefix. A UE can set up multiple PDN connections, tothe same or different APN(s).

A PDN connection in a 3GPP access contains one or more EPS bearers, eachof which is defined by a set of n-tuples with the same QoS profile. EachEPS bearer runs end-to-end between the UE and the PGW but is aconcatenation of an S5 GTP tunnel (between PGW and serving gateway, SGW)and an S1 GTP tunnel (between SGW and an evolved Node B, eNB) and aradio bearer (between eNB and UE), as illustrated in the expanded(inlaid) part of FIG. 1. GTP stands for GPRS tunneling protocol, whereGPRS is the general packet radio service.

FIG. 1 shows how bearers and PDN connections work over a 3GPP radioaccess. In a WLAN access network, only a subset of this is supportedtoday in Rel-11. This is shown in FIG. 2, discussed below.

The PGW communicates via the S2a interface to the Trusted WirelessAccess Gateway (TWAG), where a PDN connection contains one or more S2abearers. S2a supports the bearer concept in which each bearer is a GTPtunnel.

In Rel-11, there is a restriction to have only one PDN connection overWLAN which does not support the bearer concept. Therefore, the S2abearer is not end-2-end between the UE and the PGW as it is in a 3GPPaccess. However, WLAN includes the concept of Quality of Service (QoS)differentiation based on differentiated services code point (DSCP) in802.11e.

In Rel-11, each PDN connection is a logical concatenation of one or moreS2a GTP tunnels (between PGW and TWAG) and an L2 point-to-point link(between TWAG and UE).

WLAN Integration with EPC

One of the 3GPP work items in this area is referred to as SaMOG (“Studyon S2a Mobility based on GTP & WLAN access to EPC”), see 3GPP technicalreport (TR) 23.852. The aim of SaMOG is to allow a UE to gain access tothe 3GPP Evolved Packet Core (EPC) using WLAN as access technology. TheSaMOG study is performed in two phases. The first phase has already beenfinalized and released as part of 3GPP Rel-11. The result is captured in3GPP TS 23.402, section 16.2. The first phase of SaMOG provides only alimited functionality. No handover with IP address preservation between3GPP and WLAN is supported. Also, the UE is restricted to have only asingle PDN connection or a single offload connection via WLAN. Thelatter is used if an operator decides to offload the EPC; in such casean offload connection is setup. The UE's traffic is then not routed viaEPC, but from the WLAN access network directly offloaded to theInternet. This is contrary to a PDN connection that is always routed viaEPC.

The second phase of SaMOG is ongoing. Two main scenarios are beingstudied as part of the second phase. The first scenario, “single-PDNscenario”, is a small extension to the Rel-11 baseline with addedsupport for IP address preservation upon a handover between 3GPP andWLAN. The second scenario, “multi-PDN scenario”, includes not onlysupport for handover with IP address preservation, but also support formultiple PDN connections via WLAN, and support for having one or morePDN connection via 3GPP simultaneous with one or more offloadconnections via WLAN.

FIG. 3 illustrates in a baseline call flow for single-PDN scenario how aUE attaches to WLAN. This is a simplified copy of the call flow in 3GPPTS 23.402, section 16.2, with block 6 and handover support added as inthe single-PDN scenario in SaMOG, 3GPP TR 23.852. Note that the figureshows the GTP option. Proxy Mobile IP (PMIP) is possible as well, asdescribed in 3GPP TS 23.402.

FIG. 4 is a simplified copy of the multi-PDN scenario in SaMOG 3GPP TR23.852. In this example, the first connection is an offload connection.Attachment parameters for the first connection are sent as part ofauthentication (step 2). A second connection, a PDN connection in thisexample, is setup in block 5. Note that the term “handover” used in thisdocument in most cases refers to handover between 3GPP access andnon-3GPP access.

Network-Instructed Attachment to WLAN

The SaMOG study defines how a UE attaches to the network and inparticular how a PDN connection is setup via WLAN. It does not specifywhich access point (AP) the UE attaches to. Neither does it specifyunder which conditions the UE can attach to a specific AP. On a highlevel, there are two ways to control a UE when to attach, and to whichAP:

1. The first method is based on policies in the UE. These policies maybe pre-configured in the UE, or may be downloaded from a network node.In a 3GPP architecture, such a network node is called an Access NetworkDiscovery and Selection Function (ANDSF). A policy rule may say, forexample, “Attach to SSIDx when it is available”. Work is ongoing tofurther extend and refine the ANDSF policies. An example of such arefined rule is to include performance measurements, such as “Attach toSSIDx only when the load of the AP is below a certain threshold”. Suchwork is performed in 3GPP in the study “WLAN Network Selection”(WLAN_NS) of 3GPP TS 23.865. Similar work is performed within Wi-FiAlliance and their HotSpot 2.0 program.

2. In the second method, it is the network that decides when and wherethe UE shall attach. It then instructs the UE to do so by an explicitcommand. This way, policies are kept inside the network. The networkmobility function may make its decision based on measurements performedby the UE. E.g. the UE may be attached to LTE. The network theninstructs the UE to take measurements of the WLAN APs it sees. Afterreceiving the measurement results, the mobility function decides whichAP the UE shall attach to. Finally, the mobility function explicitlyinstructs the UE to attach.

IFOM and MAPCON

The two FIGS. 5 and 6 briefly define what IFOM (IP flow mobility) andMAPCON (Multi Access PDN Connectivity) is. See 3GPP TS 23.402 for a moredetailed description.

Referring to FIG. 5: IFOM capable UE is a UE that is capable of routingdifferent IP flows to the same PDN connection through different accessnetworks. TS 23.402 specifies how IFOM works. It does not specify whenthe UE shall attach to the second access. What to route via which accessis specified in ANDSF rules. IFOM is today only specified for S2c (it isa DSMIP extension). A 3GPP SA2 study on S2a/S2b-IFOM is ongoing. The SA2study has until now only addressed S2b, and may, once restarted,continue with IFOM for S2a. Today, there is no S2a-IFOM. The UE has asingle IP address for the IFOM PDN connection, even though thisconnection can be routed over two accesses.

Referring to FIG. 6: MAPCON capable UE is a UE that is capable ofrouting different simultaneously active PDN connections throughdifferent access networks. TS 23.402 specifies how MAPCON works. It doesnot specify when the UE shall attach to the second access. What to routevia which access is specified in ANDSF rules. The UE sets up two PDNconnections, one per access. Therefore, the UE has two IP addresses.

Once again, when the network decides to handover between 3GPP and WLAN,it also needs to decide what portion of this mobile device's traffic tohandover. For instance, some traffic may stay at the source access, andsome traffic may be moved. Techniques for the radio access network todecide what traffic to handover are needed.

SUMMARY

The techniques detailed herein are based on an approach whereby thenetwork e.g. the cellular RAN decides when the radio device (e.g., 3GPPUE) should attach to which AP of a WLAN. The mechanisms describedinclude a signal “handover command” that may carry an informationelement that instructs the UE what to handover.

When the network instructs the radio device what to handover, a numberof different granularities may be considered, e.g.:

1. Handover all traffic.

2. Handover all traffic belonging to a specific APN.

3. Handover all traffic belonging to a specific PDN connection.

4. Handover all traffic belonging to a specific bearer within a specificPDN connection.

Scenario 1 is covered in the prior art. The techniques detailed in thepresent disclosure are directed to scenarios 2, 3 and 4. The techniquesare tailored for a RAN-based solution, i.e., a solution when the RAN iscontrolling handovers.

The terminology used herein assumes a 3GPP Evolved Packet System (EPS)network. However, the methods described may apply just as well to other3GPP Radio Access Technologies (RATs). Accordingly, references to aneNodeB or eNB, the LTE base station, may be understood to apply as wellto a UMTS Node B or a radio network controller (RNC).

According to an aspect of the present disclosure, there is provided amethod, in a mobility function (MF) node in a communication network. Themethod comprises receiving information about a mapping to a property, ofeach of a plurality of radio bearers of a radio device for carrying datatraffic between the radio device and a first radio access network (RAN).The method also comprises determining, based on the receivedinformation, that at least one of the radio bearers can be handed overto a second RAN. The method also comprises initiating a handover commandto the radio device instructing the radio device to hand over the atleast one radio bearer to the second RAN.

According to another aspect of the present disclosure, there is provideda method, performed in a base station of a cellular RAN. The methodcomprises receiving information about a mapping to a property, of eachof a plurality of radio bearers of a radio device for carrying datatraffic between the radio device and the cellular RAN. The method alsocomprises forwarding the mapping information to an MF node for use indetermining that at least one of the radio bearers can be handed over toa wireless local area network (WLAN) RAN.

According to another aspect of the present disclosure, there is provideda mobility function (MF) node for a communication network. The MF nodecomprises a communication interface configured for communicating withone or more nodes of at least a first RAN, processing circuitry, and astorage unit storing instructions executable by said processingcircuitry whereby said MF node is operative to receive information abouta mapping to a property, of each of a plurality of radio bearers of aradio device for carrying data traffic between the radio device and afirst RAN. The MF node is also operative to determine, based on thereceived information, that at least one of the radio bearers can behanded over to a second RAN. The MF node is also operative to initiate ahandover command to the radio device instructing the radio device tohandover the at least one radio bearer to the second RAN.

According to another aspect of the present disclosure, there is provideda base station for a cellular RAN. The base station comprises a radiocommunication interface for communication with a radio device,processing circuitry, and a storage unit storing instructions executableby said processing circuitry whereby said base station is operative toreceive information about a mapping to a property, of each of aplurality of radio bearers of the radio device for carrying data trafficbetween the radio device and the cellular RAN. The base station is alsooperative to forward the mapping information to an MF node for use indetermining that at least one of the radio bearers can be handed over toa WLAN RAN.

According to another aspect of the present disclosure, there is provideda computer program product comprising computer-executable components forcausing an MF node to perform an embodiment of a method of the presentdisclosure when the computer-executable components are run on processorcircuitry comprised therein.

According to another aspect of the present disclosure, there is provideda computer program product comprising computer-executable components forcausing a base station to perform an embodiment of a method of thepresent disclosure when the computer-executable components are run onprocessor circuitry comprised therein.

According to another aspect of the present disclosure, there is provideda computer program comprising computer program code which is able to,when run on processor circuitry of an MF node, cause the node to receiveinformation about a mapping to a property, of each of a plurality ofradio bearers of a radio device for carrying data traffic between theradio device and a first RAN. The code is also able to cause the node todetermine, based on the received information, that at least one of theradio bearers can be handed over to a second RAN. The code is also ableto cause the node to initiate a handover command to the radio deviceinstructing the radio device to handover the at least one radio bearerto the second RAN.

According to another aspect of the present disclosure, there is provideda computer program comprising computer program code which is able to,when run on processor circuitry of a base station, cause the basestation to receive information about a mapping to a property, of each ofa plurality of radio bearers of a radio device for carrying data trafficbetween the radio device and the cellular RAN. The code is also able tocause the base station to forward the mapping information to an MF nodefor use in determining that at least one of the radio bearers can behanded over to a WLAN RAN.

According to another aspect of the present disclosure, there is provideda computer program product comprising an embodiment of a computerprogram of the present disclosure and a computer readable means on whichthe computer program is stored.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, step, etc.” are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, step, etc., unless explicitly stated otherwise. The steps of anymethod disclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated. The use of “first”, “second” etc.for different features/components of the present disclosure are onlyintended to distinguish the features/components from other similarfeatures/components and not to impart any order or hierarchy to thefeatures/components.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 schematically illustrates a PDN connection over a 3GPP access.

FIG. 2 schematically illustrates a PDN connection over a WLAN access.

FIG. 3 is a schematic call flow in a single-PDN scenario.

FIG. 4 is a schematic call flow in a multi-PDN scenario.

FIG. 5 schematically illustrates the concept of IFOM.

FIG. 6 schematically illustrates the concept of MAPCON.

FIG. 7 schematically illustrates communication between a radio deviceand a WLAN AP, in accordance with the present disclosure.

FIG. 8 schematically illustrates an embodiment of a cellular RAN, inaccordance with the present disclosure.

FIG. 9 is a schematic block diagram of an embodiment of a communicationnetwork, in accordance with the present disclosure.

FIG. 10 is a schematic call flow for setting up two PDN connections, inaccordance with the present disclosure.

FIG. 11 is a schematic call flow for initiating a handover, inaccordance with the present disclosure.

FIG. 12 is a schematic call flow for performing a handover, inaccordance with the present disclosure.

FIG. 13 is a schematic call flow for an example handover command, inaccordance with the present disclosure.

FIG. 14 is a schematic block diagram of an embodiment of a radio device,in accordance with the present disclosure.

FIG. 15 is a schematic block diagram of an embodiment of a mobilityfunction node, in accordance with the present disclosure.

FIG. 16 is a schematic block diagram of an embodiment of a base station,in accordance with the present disclosure.

FIG. 17 schematically illustrates an embodiment of a computer programproduct, in accordance with the present disclosure.

FIG. 18a is a schematic flow chart of an embodiment of a method of thepresent disclosure.

FIG. 18b is a schematic flow chart of another embodiment of a method ofthe present disclosure.

FIG. 19 is a schematic flow chart of another embodiment of a method ofthe present disclosure.

DETAILED DESCRIPTION

Embodiments will now be described more fully hereinafter with referenceto the accompanying drawings, in which certain embodiments are shown.However, other embodiments in many different forms are possible withinthe scope of the present disclosure. Rather, the following embodimentsare provided by way of example so that this disclosure will be thoroughand complete, and will fully convey the scope of the disclosure to thoseskilled in the art. Like numbers refer to like elements throughout thedescription.

In the discussion that follows, specific details of particularembodiments of the present disclosure are set forth for purposes ofexplanation and not limitation. It will be appreciated by those skilledin the art that other embodiments may be employed apart from thesespecific details. Furthermore, in some instances detailed descriptionsof well-known methods, nodes, interfaces, circuits, and devices areomitted so as not obscure the description with unnecessary detail. Thoseskilled in the art will appreciate that the functions described may beimplemented in one or in several nodes. Some or all of the functionsdescribed may be implemented using hardware circuitry, such as analogueand/or discrete logic gates interconnected to perform a specializedfunction, ASICs, PLAs, etc. Likewise, some or all of the functions maybe implemented using software programs and data in conjunction with oneor more digital microprocessors or general purpose computers. Wherenodes that communicate using the air interface are described, it will beappreciated that those nodes also have suitable radio communicationscircuitry. Moreover, the technology can additionally be considered to beembodied entirely within any form of computer-readable memory, includingnon-transitory embodiments such as solid-state memory, magnetic disk, oroptical disk containing an appropriate set of computer instructions thatwould cause a processor to carry out the techniques described herein.

Hardware implementations of the present disclosure may include orencompass, without limitation, digital signal processor (DSP) hardware,a reduced instruction set processor, hardware (e.g., digital or analog)circuitry including but not limited to application specific integratedcircuit(s) (ASIC) and/or field programmable gate array(s) (FPGA(s)), and(where appropriate) state machines capable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors or one or more controllers, and theterms computer, processor, and controller may be employedinterchangeably. When provided by a computer, processor, or controller,the functions may be provided by a single dedicated computer orprocessor or controller, by a single shared computer or processor orcontroller, or by a plurality of individual computers or processors orcontrollers, some of which may be shared or distributed. Moreover, theterm “processor” or “controller” also refers to other hardware capableof performing such functions and/or executing software, such as theexample hardware recited above.

The discussion that follows frequently refers to “UEs,” which is the3GPP term for end user radio devices. It should be appreciated, however,that the techniques and apparatus described herein are not limited to3GPP UEs, but are more generally applicable to end user wireless devices(e.g., portable cellular telephones, smartphones, wireless-enabledtablet computers, etc.) that are useable in cellular systems. It shouldalso be noted that the current disclosure relates to end user wirelessdevices that support both a wireless local area network (WLAN)technology, such as one or more of the IEEE 802.11 standards, and awide-area cellular technology, such as any of the wide-area radio accessstandards maintained by 3GPP. End user devices are referred to in Wi-Fidocument as “stations,” or “STA”—it should be appreciated that the term“UE” as used herein should be understood to refer to a STA, andvice-versa, unless the context clearly indicates otherwise.

As noted above, many smartphones on the market today support Wi-Ficonnectivity in addition to supporting one or more cellular radio-accesstechnologies (RATs), such as the several RATs standardized by 3GPP. Inan operator controlled Wi-Fi scenario, a UE may usually be served withcommunication through the cellular 3GPP network. Occasionally, e.g.,when moving indoors, or when cellular performance deteriorates and thereis good Wi-Fi coverage, it would be advantageous, from anetwork-performance perspective or a user-experience perspective, orboth, for the UE to receive services through Wi-Fi instead of throughthe 3GPP radio access network.

FIG. 7 illustrates a radio device/UE 100 able to communicate, using802.11-specified protocols, with a Wi-Fi access point 110 of a WLAN RAN115. Downlink communication 120 is directed from the Wi-Fi access point110 to the UE 100, while uplink communication 130 is directed from theUE 100 to the Wi-Fi access point 110.

For the radio device 100 to find an access point to connect to, a beaconsignal may be transmitted from the Wi-Fi access point 110. This beaconsignal indicates details about the access point and provides the radiodevice with enough information to be able to send a request for access.Accessing a Wi-Fi access point includes an information exchange betweenUE 100 and Wi-Fi Access point 110, including, for example, proberequests and responses, and authentication requests and response. Theexact content of these sequences are omitted for clarity.

FIG. 8 illustrates a portion of the LTE radio access network 200 andcontroller nodes. The LTE network is more formally known as the EvolvedUMTS Terrestrial Radio Access Network (E-UTRAN), and includes basestations 220, 230, 240, called enhanced NodeBs (eNBs or eNodeBs), whichprovide the E-UTRA user plane and control plane protocol terminationstowards the User Equipment (UE) 100. The eNBs are interconnected witheach other by means of the X2 interface 250, 252, 254. The eNBs are alsoconnected by means of the S1 interface 260, 262, 264, 266 to the EvolvedPacket Core (EPC), and more specifically to Mobility Management Entities(MMEs) 210, 211 of a core network, by means of the S1-MME interface, andto the Serving Gateway (S-GW) 210, 211 by means of the S1-U interface.The S1 interface supports many-to-many relation between MMEs/S-GWs andeNBs.

The eNB hosts functionalities such as Radio Resource Management (RRM),radio bearer control, admission control, header compression of userplane data towards serving gateway, and routing of user plane datatowards the serving gateway. The MME is the control node that processesthe signalling between the UE and the core network. The main functionsof the MME are related to connection management and bearer management,which are handled via Non Access Stratum (NAS) protocols. The PGW is theanchor point for UE mobility, and also includes other functionalitiessuch as temporary DL data buffering while the UE is being paged, packetrouting and forwarding the right eNB, gathering of information forcharging and lawful interception. A PDN Gateway (P-GW), not shown inFIG. 8, is the node responsible for UE IP address allocation, as well asfor Quality-of-Service (QoS) enforcement.

FIG. 9 illustrates a communication network 1 where the LTE radio accessparts 220, 230 of the LTE RAN 200 and a Wi-Fi wireless access point 110of the WLAN 115 are both connected to the same P-GW 340. A UE 100 iscapable of being served both from the Wi-Fi Access Point 110 and the LTEeNBs 220, 230. FIG. 9 illustrates one possible way of connecting a Wi-Fiaccess network 115 to the same core network as the 3GPP-specified accessnetwork 200. It should be noted that the presently disclosed techniquesare not restricted to scenarios where the Wi-Fi access network isconnected in this way; scenarios where the networks are more separate,e.g., as illustrated in FIGS. 7 and 8, are also possible scenarios.

There can be an interface 370 between the Wi-Fi and 3GPP domains,whereby the two networks (cellular 200 and WLAN 115) can exchangeinformation that can be used to facilitate on steering traffic over theright network. One example of such information exchanged via theinterface 370 is load conditions in the two networks. The two networkscan also exchange information with regard to the context of the UE 100,so that each can be aware of whether the UE is being served by the othernetwork, as well as some details of the connection over the othernetwork (e.g. traffic volume, throughput, etc. . . . )

It should be noted that an access-point controller (AC) functionalityexists in the Wi-Fi domain that controls the Wi-Fi AP. Thisfunctionality, though not depicted in the figure for the sake ofclarity, can be physically located in 110, 340 or another separatephysical entity.

RAN-Controlled Handover of all UE Traffic Belonging to an APN

The call flow of FIGS. 10-12 describes how a RAN-controlled handover ofall UE traffic to a particular APN would work. There is a mobilityfunction (MF) that decides when to handover traffic between theaccesses. The MF may be co-located with another functional unit, e.g.,the base station (e.g. eNB).

With reference to FIG. 10 (spanning drawing pages 6 and 7), two PDNconnections are setup via LTE (block 1 and block 12). The first PDNconnection is towards APN1 (e.g., the Internet APN), whereas the secondPDN connection is towards APN2 (e.g., the IMS APN). The first PDNconnection consists of only a single bearer. The second PDN connectionhas two bearers; the setup of the second bearer is initiated from thePGW 340. The setup procedures in this example are simplified and basedon 3GPP TS 23.401, sections 5.3.2 and 5.4.1. It is noted that FIG. 10indicates the presence of an authentication, authorization andaccounting (AAA) server 1020, although it does not actively take part inthe call flow shown in the figure (but does take part in the call flowof FIG. 12).

One new operation in the setup of the connections and bearers lies instep 6 where the MME 1010 sends a mapping (bearer ID→APN) as part of theS1-MME signalling. The eNB then sends this mapping to the MF (step 10).Currently the RAN 200 (eNB 220, MF 15) is not aware of the relationbetween bearers and the APN or the PDN Connection.

Referring to FIG. 11, once the PDN connections have been setup, the MF15 requests measurements from the UE 100 (step 32). Eventually, the MFmay decide to initiate a handover (step 33). In this example, it decidesto handover APN1. It instructs the UE 100 to do so by indicating APN1 inthe handover command (step 34). Because the MF is now aware of themapping between the bearer ID and the APN, the MF 15 can make a decisionbased on APN. This is enabled by the bearer-to-APN mappings that werepreviously sent to the MF. The MF may base its decision on measurementscombined with policies.

Example

The MF 15 may be aware of the Quality-of-Service Class Indicator (QCI)for each bearer (it may have received this as part of step 10, 21, 29).BearerID=a and BearerID=b may have a QCI corresponding to “best effort”,whereas BearerID=c may have a QCI corresponding to “voice”. If the MF,based on the received measurement reports, concludes that best effortcan be moved to WLAN, but not voice, then it may instruct to move APN1to WLAN 115 as all the bearers associated with APN1 (bearer a) fit thiscriteria (best effort and not voice).

The actual attachment to WLAN and the handover procedure (block 35) isillustrated in FIG. 12 based on the procedure of FIG. 4—Future multi-PDNscenario—in the background section. Note that in the presently disclosedprocedure, the TWAG 1000 informs the MF 15 of the mapping (step 45). Inthis example, the first PDN connection to APN1 only has a single bearer.If it would have had multiple bearers, the MF would inform the TWAG forthe mapping of each individual bearer.

Note that the new bearerID=x corresponds to the original bearerID=a onthe LTE side. The value of x and a may be the same, but this is notnecessarily the case. In today's 3GPP specification the bearerID valuesare not kept upon a handover between LTE and WLAN (in general, these arenot kept between 3GPP and a non-3GPP access).

In the example call flow of FIGS. 10-12, subsequent measurements can beperformed after the handover to WLAN 115. Block 31 can thus be repeatedand eventually the MF 15 may take additional decisions; e.g., to alsomove the second PDN connection to APN2 to WLAN, or to move the first PDNconnection to APN1 back to LTE 200. Moving from LTE to WLAN would be asimilar extension to existing handover procedures. Also in thisdirection, the MF includes an APN identifier in the handover command tothe UE 100, and the eNB 220 sends the new mappings to the MF 15.

An advantage of the solution above is that it reduces the impact on thenetwork nodes (PGW, SGW, MME, etc). The solution assumes aMAPCON-capable UE 100. These UEs are now appearing on the market. Notethat in this solution, the bearerID values are kept within the networkand do not need to be known by the UE for the purpose of selectivehandover.

If the measurements (step 32) are always to be reported via LTE, then aproblem arises when all PDN connections of a UE 100 are moved to WLAN115. The UE will then get detached from LTE 200. To prevent this, the UEcould keep at least one PDN connection over LTE. This may be achieved bya policy—e.g., if there is a PDN connection over LTE to a particular APN(e.g., IMS), then the network 1 never instructs to move that APN to WLAN115. Alternatively, a “dummy PDN connection” could be used. The solepurpose of such a PDN connection would be to keep the LTE connection up.Such PDN connection is just a normal PDN connection. The difference isthat it would not be used to carry any user plane traffic, although itcould be used to do so. As any PDN connection, the dummy PDN connectionwould be towards a particular APN. This may be a “dummy APN” that isexplicitly configured by the operator for the sole purpose of setting upa dummy PDN connection. The setup of a PDN connection is done by the UE100 prior to handover. The network 1 may trigger the UE to do so, e.g.by indicating this in the handover command (step 34).

In the example above, the bearerID is sent to the MF 15 from the eNB 220and TWAG woo respectively. However, any other network node that is awareof the bearerID could send this information. On the 3GPP access, thiscould be MME 1010 or SGW 330 or PGW 340. On the WLAN access, this couldbe PGW 340.

RAN-Controlled Handover of all UE Traffic Belonging to a Specific PDNConnection

The current 3GPP specification mandates that all PDN connections to aspecific APN are always routed via the same access. In this respect,handover of a specific PDN connection is not relevant. However, theprocedure described in the previous section could be upgraded to alsosupport handovers on a PDN connection granularity instead of an APNgranularity.

A PDN connection can be uniquely identified by the combination of APNand IP address/prefix of the PDN connection. So if the mappingsdescribed in the previous section contain (bearerID→APN+IP) then the MF15 can make its decision on PDN connection granularity. The MF wouldthen signal APN+IP to the UE 100 as part of the handover command. Adisadvantage of this approach is that the IP address/prefix is not knownby the eNB 220, and is not always known by MME 1010 and SGW 330 intoday's specifications. This could of course be added for this purpose.

An alternative solution would be based on using the existing linkedbearer identification (LBI). Each PDN connection has at least onebearer, the so called default bearer. That default bearer gets assignedthe LBI. When any additional bearer for the same PDN connection issetup, then control signalling related to the setup of that additionalbearer also carries the LBI. The LBI is thus available in all relevantnetwork nodes and can be used to uniquely identify the PDN connection.The node that sends mapping to the MF would then send (bearerID→LBI). Inthis case the eNB/TWAG/etc and MF need not be aware of the UE IPaddresses. The MF could then signal LBI to the UE as part of thehandover command.

The alternative solution implies that the UE 100 needs to be aware ofbearerIDs. Today this is already supported for those bearers over LTE.However, for WLAN, there is no bearer concept. As a consequence, the UEis not aware of any bearerID for PDN connections over WLAN. However, itis also possible to introduce the bearer concept on WLAN, in which casebearer definitions can be sent from the Trusted Wireless Access Gateway(TWAG) to the UE. This may be extended by also sending the bearerID(e.g., S2a bearer ID and the LBI).

RAN-Controlled Handover of all UE Traffic Belonging to a Specific Bearerwithin a Specific PDN

The granularity of the traffic to handover can be further refined tobearer level. This would require an IFOM-capable UE 100.

Continuing the example from the previous section: The MF 15 may be awareof the Quality-of-Service (QCI) for each bearer (it may have receivedthis as part of step 10, 21, 29). BearerID=a andBearerID=b may have aQCI corresponding to “best effort”, whereas BearerID=c may have a QCIcorresponding to “voice”. If the MF, based on the received measurementreports, concludes that best effort traffic can be moved to WLAN 115,but not voice traffic, then it may instruct to move BearerID=a andBearerID=b to WLAN. Or the instruction can contain the QCI(s) of thebearers to be moved without explicitly stating the bearer IDs.

To achieve this, the MF 15 indicates the BearerIDs and an “IFOM flag” inthe handover command. If the QCI of each bearer is also know to the UE100, then instead of indicating specific BearerIDs, the MF alternativelyindicates “all bearers that have QCI=x”. The UE in its turn indicates“IFOM” in the attachment to WLAN 115. In the example above, the UEperforms an IFOM handover to WLAN for both active PDN connections.

Note that an IFOM PDN connection is active over multiple accessessimultaneously. The UE will therefore stay connected over LTE and no“dummy PDN connection” (as described above) is needed.

A disadvantage of this approach may be that IFOM over S2a is notsupported in today's specifications. Only IFOM for S2c is supported.However, there are no real deployments. A study in 3GPP SA2 to introduceIFOM over S2a is ongoing. Another disadvantage, already mentioned in theprevious section, may be that WLAN currently does not support the bearerconcept. Also, for the handover solution based on IFOM PDN connection,it will be required that the UE 100 is made aware of the bearerIDs forthose bearers over WLAN 115.

MF Making Decisions Based on QCI

In the previous three sections, examples are given where the MF 15considers QCI in making its decisions regarding what to handover. Thissection presents details of how QCI can be used to refine thegranularity of traffic steering.

The QCI value range is 255. Ten values are standardized. Using more than10 values allows traffic steering with high granularity. According tothis approach, the 3GPP core network, prior to sending the handovercommand, assigns different QCI values to different types of traffic toallow for a suitable traffic steering granularity. For example, the 3GPPcore network may assign QCI value 17 to a video streaming and QCI value23 for web browsing. The MF may then indicate to the UE that aparticular QCI value, e.g., QCI value of 23, should be offloaded toWLAN. In this particular example, this would ensure that the videostreaming traffic is kept on LTE while the web browsing is steered toWLAN.

The setting of the QCI is done in the core network, which may be awareof not only the type of traffic but may also have more detailedinformation about the services, whereas the access network (LTE or WLAN)usually does not have such information. For example, the core networkmay be able to identify YouTube traffic from peer-to-peer file sharing,but the access network does usually not have such information. If thisis the case, the core network may give different QCI values for theYouTube traffic and the peer-to-peer file sharing which can then be usedto steer these services individually. One alternative is that if the MFperforms the traffic steering but the core aids the MF in doing theservice differentiation by first giving different QCI values todifferent services and then indicating to the MF that QCI X can be movedto WLAN, but that QCI Y should not be moved to WLAN. Note that the QCIvalue of a bearer can also be changed after setup, by means of theexisting bearer modification procedures.

It may also be possible to have some semi-static mapping that can beused to differentiate bearers that can be moved or not. For example, QCIrange a to b can be allocated to bearers that shouldn't be moved to WLAN115, while QCI range a+n to b+n is set for those that can be moved.Initially, when a bearer is setup in 3GPP it will take a QCI valuebetween a and b. If it is later decided that this bearer is to be moved,then a bearer modification procedure is initiated to change the QCIvalue of that bearer to the original value plus n, implicitly tellingthe UE that this bearer is to be moved to WLAN.

Possible Handover Command Implementation

This section describes one possibility on how the handover command (step34 in the call flow of FIG. 11) can be implemented. This implementationis valid when the handover command is sent via the 3GPP RAN 200signalling.

With reference to FIG. 13, the 3GPP RAN 200 signals to the UE 100 anRRCConnectionReconfiguration message containing an information elementthat in turn contains all or a subset of the information necessary toperform the mobility to WLAN 115. In the below example this informationelement is called MobilityControlInfoWlan. The information elementMobilityControlWlan may be optionally present in theRRCConnectionReconfiguration message meaning that it is only included bythe 3GPP network when mobility to WLAN shall be performed, if not theinformation element will be omitted.

Note that the message RRCConnectionReconfiguration and informationelement MobilityControlWlan may contain other information than what isshown in this example. However, to simplify the example, only theparameters related to the above text have been included.

The UE 100 will, upon reception of an RRCConectionReconfigurationmessage determine if the information element mobilityControlWlan isincluded and in such case perform the WLAN offloading as explained inthe above embodiments.

-- ASN1START RRCConnectionReconfiguration ::= SEQUENCE {  mobilityControlInfoWlan   MobilityControlInfoWlan       OPTIONAL, }MobilityControlInfoWlan information element -- ASN1STARTMobilityControlInfoWlan ::= SEQUENCE {   targetSSID     OCTET STRING,  apn-identifier   APN-Identifier     OPTIONAL,   bearer-identifier  Bearer-Identifer     OPTIONAL,   qci-identifier   QCI-Identifier    OPTIONAL,   linkedBearerIdentifier   LinkBearerIdentify    OPTIONAL,   dummy-apn-identifier   APN-Identifier     OPTIONAL }APN-Identifier ::=   SEQUENCE (SIZE (1..10)) OF OCTET_STRINGBearer-Identifier ::= SEQUENCE (SIZE (1..10)) of INTEGER (0..128)QCI-Identifier ::=   SEQUENCE (SIZE (1..10)) OF INTEGER (0..128)LinkBearerIdentify ::=   SEQUENCE (SIZE (1..10)) OF INTEGER (0..128) --ASN1STOP

The ranges given in the above example commands are not critical—otherranges are also possible.

There may be 0, 1 or more than 1 instances of apn-identifier,bearer-identifier, qci-identifier, and linkedBearerIdntifier in theMobilityControlInfoWlan information element. For example, if thehandover command instructs the UE 100 to handover two APNs, thenMobilityControlInfoWlan contains two occurrences of apn-identifier.

When the dummy-apn-identifier is present, it serves as a trigger for theUE to setup a PDN connection to the dummy APN. The MF would include thatif it instructs the UE 100 to move the last bearer from LTE 200 to WLAN115, but it wants the UE to stay connected over LTE. In the example herethe APN string is sent to the UE. Alternatively, the string is alreadyavailable in the UE; e.g. by pre-configuration, by ANDSF, or received atattachment. In such case the string would not be needed in theRRCConnectionReconfiguration message. Instead, a boolean triggerindicator would suffice.

Several of the techniques and methods described above may be implementedusing radio circuitry and electronic data processing circuitry providedin a radio device 100. FIG. 14 illustrates features of an example radiodevice/UE 100 according to several embodiments of the presentdisclosure.

The radio device 100, which may be a UE configured for operation with anLTE network (E-UTRAN) and that also supports Wi-Fi, for example,comprises a transceiver unit 1520 for communicating with one or morebase stations 220, 230, 240 as well as a processing circuit 1510 forprocessing the signals transmitted and received by the transceiver unit1520. Transceiver unit 1520 includes a transmitter 1525 coupled to oneor more transmit antennas 1528 and receiver 1530 coupled to one or morereceiver antennas 1533. The same antenna(s) 1528 and 1533 may be usedfor both transmission and reception. Receiver 1530 and transmitter 1525use known radio processing and signal processing components andtechniques, typically according to a particular telecommunicationsstandard such as the 3GPP standards for LTE. Note also that transmitterunit 1520 may comprise separate radio and/or baseband circuitry for eachof two or more different types of radio access network, such asradio/baseband circuitry adapted for E-UTRAN access and separateradio/baseband circuitry adapted for WiFi access. The same applies tothe antennas—while in some cases one or more antennas may be used foraccessing multiple types of networks, in other cases one or moreantennas may be specifically adapted to a particular radio accessnetwork or networks. Because the various details and engineeringtrade-offs associated with the design and implementation of suchcircuitry are well known and are unnecessary to a full understanding ofthe disclosure, additional details are not shown here.

Processing circuit 1510 comprises one or more processors 1540 coupled toone or more memory devices 1550 that make up a data storage memory 1555and a program storage memory 1560. Processor 1540, identified as CPU1540 in FIG. 14, may be a microprocessor, microcontroller, or digitalsignal processor, in some embodiments. More generally, processingcircuit 1510 may comprise a processor/firmware combination, orspecialized digital hardware, or a combination thereof. Memory 1550 maycomprise one or several types of memory such as read-only memory (ROM),random-access memory, cache memory, flash memory devices, opticalstorage devices, etc. Because radio device 100 supports multiple radioaccess networks, processing circuit 1510 may include separate processingresources dedicated to one or several radio access technologies, in someembodiments. Again, because the various details and engineeringtrade-offs associated with the design of baseband processing circuitryfor mobile devices are well known and are unnecessary to a fullunderstanding of the disclosure, additional details are not shown here.

Typical functions of the processing circuit 1510 include modulation andcoding of transmitted signals and the demodulation and decoding ofreceived signals. In several embodiments of the present disclosure,processing circuit 1510 is adapted, using suitable program code storedin program storage memory 1560, for example, to carry out one of thetechniques described above for access network selection. Of course, itwill be appreciated that not all of the steps of these techniques arenecessarily performed in a single microprocessor or even in a singlemodule.

Similarly, several of the techniques and processes described above canbe implemented in a network node, such as an eNodeB 220 or other node ina 3GPP network. FIG. 15 is a schematic illustration of an MF node 15 inwhich a method embodying any of the presently described network-basedtechniques can be implemented. A computer program for controlling thenode 15 to carry out a method embodying the present disclosure is storedin a program storage 30, which comprises one or several memory devices.Data used during the performance of a method embodying the presentdisclosure is stored in a data storage 20, which also comprises one ormore memory devices. During performance of a method embodying thepresent disclosure, program steps are fetched from the program storage30 and executed by a Central Processing Unit (CPU) 10, retrieving dataas required from the data storage 20. Output information resulting fromperformance of a method embodying the present disclosure can be storedback in the data storage 20, or sent to an Input/Output (I/O)communication interface 40, which includes a network interface forsending and receiving data to and from other network nodes and which mayalso include a radio transceiver for communicating with one or moreradio devices 100.

Accordingly, in various embodiments of the disclosure, processingcircuits, such as the CPU 10 in FIG. 15, are configured to carry out oneor more of the techniques described in detail above. Likewise, otherembodiments include radio network controllers including one or more suchprocessing circuits. In some cases, these processing circuits areconfigured with appropriate program code, stored in one or more suitablememory devices, to implement one or more of the techniques describedherein. Of course, it will be appreciated that not all of the steps ofthese techniques are necessarily performed in a single microprocessor oreven in a single module.

FIG. 16 schematically illustrates an embodiment of a base station 220(also relevant for the base stations 230 and 240) of the presentdisclosure. The base station 220 comprises processor circuitry 160 e.g.a central processing unit (CPU). The processor circuitry 160 maycomprise one or a plurality of processing units in the form ofmicroprocessor(s). However, other suitable devices with computingcapabilities could be comprised in the processor circuitry 160, e.g. anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or a complex programmable logic device (CPLD). Theprocessor circuitry 160 is configured to run one or several computerprogram(s) or software 171 (see also FIG. 17) stored in a storage 161 ofone or several storage unit(s) e.g. a memory. The storage unit isregarded as a computer readable means as discussed herein and may e.g.be in the form of a Random Access Memory (RAM), a Flash memory or othersolid state memory, or a hard disk, or be a combination thereof. Theprocessor circuitry 160 may also be configured to store data in thestorage 161, as needed. The base station 220 also comprises acommunication interface 160 comprising a radio communication interfacefor radio communication with one or more radio devices 100, as well asan interface for communication with other nodes in the 3GPP network.

FIG. 17 illustrates a computer program product 170. The computer programproduct 170 comprises a computer readable medium 172 comprising acomputer program 171 in the form of computer-executable components 171.The computer program/computer-executable components 171 may beconfigured to cause an MF node 15 or a base station 220, e.g. asdiscussed herein to perform an embodiment of a method of the presentdisclosure. The computer program/computer-executable components may berun on the processor circuitry 10/160 of the node 15/base station 220for causing it to perform the method. The computer program product 170may e.g. be comprised in a storage unit or memory 30/161 comprised inthe node 15/base station 220 and associated with the processor circuitry10/160. Alternatively, the computer program product 170 may be, or bepart of, a separate, e.g. mobile, storage means, such as a computerreadable disc, e.g. CD or DVD or hard disc/drive, or a solid statestorage medium, e.g. a RAM or Flash memory.

FIG. 18a is a schematic flow chart of an embodiment of a method of thepresent disclosure. The method is performed in a mobility function (MF)node 15 in a communication network 1. The MF node 15 receives S1information about a mapping to a property, of each of a plurality ofradio bearers of a radio device 100 for carrying data traffic betweenthe radio device 100 and a first RAN 200 or 115. The property may e.g.be APN, PDN connection or bearer ID, as discussed herein. Based on thereceived S1 information, the MF node 15 determines S2 that at least oneof the radio bearers can be handed over to a second RAN 115 or 200.Then, the MF node 15 initiates S3 a handover command to the radio device100 instructing the radio device to hand over the at least one radiobearer to the second RAN, e.g. by instructing a base station 220, 230 or240 to send such a handover command to the radio device 100.

FIG. 18b is a schematic flow chart of another embodiment of a method ofthe present disclosure. In addition to the steps S1-S3 discussed withreference to FIG. 18a , the MF node 15 may receive S4 measurement dataof the mobile terminal 100, said measurement data relating tomeasurements made by the mobile terminal on the first and/or second RAN115/200. Then, the determining S2 that the at least one radio bearerbetween the radio device 100 and a first RAN can be handed over to asecond RAN may be based also on said received measurement data incombination with policies predefined in the MF node 15. Additionally oralternatively, the MF node 15 may receive S5 quality-of-service classindicator (QCI) information for each of the radio bearers, e.g. from acore network (CN) node via a base station. The QCI information may e.g.be related to the type of data traffic of each radio bearer. Then, saiddetermining S2 may also be based on said QCI information.

FIG. 19 is a schematic flow chart of another embodiment of a method ofthe present disclosure. This method is performed by a base station 220,230 or 240 of a cellular RAN 200. The base station receives S11information about a mapping to a property, of each of a plurality ofradio bearers of a radio device 100 for carrying data traffic betweenthe radio device 100 and the cellular RAN 200. Then, the base stationforwards S12 the mapping information to an MF node 15 for use indetermining that at least one of the radio bearers can be handed over toa WLAN RAN 115.

With the solutions described herein, a RAN 200 or 115 is enabled to moveonly part of a UE's 100 traffic between different accesses, instead ofmoving all of the UE's traffic. It will be appreciated by the person ofskill in the art that various modifications may be made to the abovedescribed embodiments without departing from the scope of the presentdisclosure. For example, it will be readily appreciated that althoughthe above embodiments are described with reference to parts of a 3GPPnetwork, an embodiment of the present disclosure will also be applicableto like networks, such as a successor of the 3GPP network, having likefunctional components. Therefore, in particular, the terms 3GPP andassociated or related terms used in the above description and in theenclosed drawings and any appended claims now or in the future are to beinterpreted accordingly.

Examples of several embodiments of the present disclosure have beendescribed in detail above, with reference to the attached illustrationsof specific embodiments. Because it is not possible, of course, todescribe every conceivable combination of components or techniques,those skilled in the art will appreciate that the present disclosure canbe implemented in other ways than those specifically set forth herein,without departing from essential characteristics of the disclosure. Thepresent embodiments are thus to be considered in all respects asillustrative and not restrictive.

Below follow some other aspects and embodiments of the presentdisclosure.

In some embodiments of the present disclosure, the received S1information about mapping to a property comprises information about towhich APN each of the radio bearers is mapped, and the radio bearerscomprise at least one radio bearer mapped to a first APN and at leastone radio bearer mapped to a second APN, wherein the determining S2comprises determining that the at least one radio bearer mapped to thefirst APN should be handed over to the second RAN 200 or 115.

In some embodiments of the present disclosure, the received S1information about mapping to a property comprises information about towhich PDN connection each of the radio bearers is mapped, and the radiobearers comprise at least one radio bearer mapped to a first PDNconnection and at least one radio bearer mapped to a second PDNconnection, wherein the determining S2 comprises determining that the atleast one radio bearer mapped to the first PDN connection should behanded over to the second RAN 200 or 115. In some embodiments, thereceived S1 information comprises IP addresses associated with each ofthe radio bearers, and/or the linked bearer identification (LBI)associated with each of the radio bearers.

In some embodiments of the present disclosure, the received S1information about mapping to a property comprises bearer IDs for each ofthe radio bearers, and the determining S2 comprises determining that atleast one of the radio bearers as identified by its bearer ID should behanded over to the second RAN 200 or 115.

In some embodiments of the present disclosure, the determining S2comprises determining that bearers associated with a specific QCI orrange of QCIs can be handed over to the second RAN 115 or 200.

In some embodiments of the present disclosure, the first RAN is acellular RAN 200 and the second RAN is a WLAN 115. In some embodiments,the received S1 information about mapping to a property is received S1from a CN node via a base station 220, 230 or 240 in the first RAN 200.

In some other embodiments of the present disclosure, the first RAN is aWLAN 115 and the second RAN is a cellular RAN 200. In some embodiments,the received S1 information about the mapping is received S1 from atrusted wireless access gateway (TWAG) 1000 associated with the WLAN115.

In some embodiments of the present disclosure, the handover command isconfigured to instruct the radio device 100 to hand over at least onebut fewer than all of the radio bearers of the radio device.

In some embodiments of the present disclosure, the handover commandcomprises a Radio Resource Control (RRC) Connection Reconfigurationmessage comprising one or more parameters used for the hand over.

In some embodiments of the present disclosure, the mapping informationis received S11 by the base station 220, 230 or 240 from a core networknode, e.g. from a mobility management entity (MME) 1010, before it isforwarded S12 to the MF node 15.

According to an aspect of the present disclosure, there is provided amobility function (MF) node 15 for a communication network 1. The MFnode 15 comprises means (e.g. the processing circuitry 10 in cooperationwith the communication interface 40) for receiving S1 information abouta mapping to a property, of each of a plurality of radio bearers of aradio device 100 for carrying data traffic between the radio device 100and a first RAN 200 or 115. The MF node also comprises means (e.g. theprocessing circuitry 10) for determining S2, based on the received S1information, that at least one of the radio bearers can be handed overto a second RAN 115 or 200. The MF node also comprises mans (e.g. theprocessing circuitry 10 in cooperation with the communication interface40) for initiating S3 a handover command to the radio device 100instructing the radio device to hand over the at least one radio bearerto the second RAN.

According to another aspect of the present disclosure, there is provideda base station 220, 230 or 240 for a cellular RAN 200. The base stationcomprises means (e.g. the processing circuitry 160 in cooperation withthe communication interface 162) for receiving S11 information about amapping to a property, of each of a plurality of radio bearers of aradio device 100 for carrying data traffic between the radio device 100and the cellular RAN 200. The base station also comprises means (e.g.the processing circuitry 160 in cooperation with the communicationinterface 162) for forwarding S12 the mapping information to an MF node15 for use in determining that at least one of the radio bearers can behanded over to a WLAN RAN 115.

According to another aspect of the present disclosure, there is provideda method, in a base station 220, 230 or 240 of a cellular radio accessnetwork 200. The method comprises receiving a mapping of radio bearersto corresponding Access Point Names (APN) for a mobile terminal 100. Themethod also comprises forwarding the mapping to a mobility function (MF)node 15, for use in determining whether all or part of data traffic withthe mobile terminal 100 can be handed over to a wireless local areanetwork (WLAN) 115 connection.

According to another aspect of the present disclosure, there is provideda method, in a mobility function (MF) node 15. The method comprisesreceiving a mapping of radio bearers to corresponding Access Point Names(APNs) for a mobile terminal 100. The method also comprises receivingmeasurement data from or for the mobile terminal 100. The method alsocomprises determining, based on the measurement data, that all or partof data traffic between the mobile terminal and a first radio accessnetwork (RAN) 200 or 115 can be handed over to a second RAN 200 or 115.The method also comprises sending a handover command to the mobileterminal 100 instructing the mobile terminal to handover all or part ofthe data traffic to the second RAN.

In some embodiments, the data traffic between the mobile terminal 100and the first RAN comprises traffic two and/or from two or more APNs,wherein said determining comprises deciding that some but less than allof the traffic should be handed over to the second RAN, and wherein saidhandover command instructs the mobile terminal to hand over trafficcorresponding to at least one but fewer than all of the APNs.

In some embodiments, the determining is based on a quality-of-serviceclass indicator (QCI) for each of one or more of the radio bearers.

In some embodiments, the first RAN is a cellular RAN 200 and the secondRAN is a wireless local-area network (WLAN) 115. In some embodiments,the mapping is received from a base station 220, 230 or 240 in the firstRAN 200.

In some other embodiments, the first RAN is a wireless local-areanetwork (WLAN) 115 and the second RAN is a cellular RAN 200. In someembodiments, the mapping is received from a trusted wireless accessgateway (TWAG) 1000 associated with the WLAN 115.

In some other embodiments, the mapping identifies multiple PDNconnections for the mobile terminal 100, and wherein said handovercommand instructs the mobile terminal to hand over at least one butfewer than all of the PDN connections.

In some other embodiments, the handover command instructs the mobileterminal 100 to hand over at least one but fewer than all of the bearersfor the mobile terminal.

In some embodiments, said determining that all or part of data trafficbetween the mobile terminal 100 and a first radio access network (RAN)200 or 115 can be handed over to a second RAN 200 or 115 comprisesdetermining that individual bearers should be handed over based on aquality-of-service class indicator (QCI) corresponding to each bearer.In some embodiments, said handover command instructs the mobile terminalto hand over bearers associated with a specific QCI or range of QCIs. Insome embodiments, the method further comprises receiving QCI informationfor radio bearers for the mobile terminal 100 from a core network node1010.

In some embodiments, said handover command comprises a Radio ResourceControl (RRC) Connection Reconfiguration message comprising one or moreparameters used for the hand over.

According to another aspect of the present disclosure, there is provideda mobility function (MF) node 15 comprising a communication interface 40configured for communicating with one or more nodes of at least a firstradio access network (RAN) 200 or 115 and further comprising aprocessing circuit configured to carry out an embodiment of a method ofthe present disclosure.

According to another aspect of the present disclosure, there is provideda mobility function (MF) node 15, comprising a receiver unit adapted toreceive a mapping of radio bearers to corresponding Access Point Names(APNs) for a mobile terminal 100 and receive measurement data from orfor the mobile terminal. The MF node 15 also comprises a handoverdecision unit adapted to determine, based on the measurement data, thatall or part of data traffic between the mobile terminal 100 and a firstradio access network (RAN) 200 or 115 can be handed over to a second RAN200 or 115. The MF node 15 also comprises a sending unit adapted tosend, under the control of the handover decision unit, a handovercommand to the mobile terminal 100 instructing the mobile terminal tohand over all or part of the data traffic to the second RAN.

The present disclosure has mainly been described above with reference toa few embodiments. However, as is readily appreciated by a personskilled in the art, other embodiments than the ones disclosed above areequally possible within the scope of the present disclosure, as definedby the appended claims.

1-23. (canceled)
 24. A method, in a mobility function (MF) node, in acommunication network, the method comprising: receiving informationabout a mapping to a property, of each of a plurality of radio bearersof a radio device for carrying data traffic between the radio device anda first radio access network (RAN); determining, based on the receivedinformation, that at least one of the radio bearers can be handed overto a second RAN; and initiating a handover command to the radio deviceinstructing the radio device to hand over the at least one radio bearerto the second RAN.
 25. The method of claim 24, further comprising:receiving measurement data of the mobile terminal, said measurement datarelating to measurements made by the mobile terminal on the first and/orsecond RAN; wherein the determining that the at least one radio bearerbetween the radio device and a first RAN can be handed over to a secondRAN is based also on said received measurement data in combination withpolicies predefined in the MF node.
 26. The method of claim 24, whereinthe information about mapping to a property comprises information aboutto which Access Point Name (APN) each of the radio bearers is mapped,and wherein the radio bearers comprise at least one radio bearer mappedto a first APN and at least one radio bearer mapped to a second APN,wherein said determining comprises determining that the at least oneradio bearer mapped to the first APN should be handed over to the secondRAN.
 27. The method of claim 24, wherein the information about mappingto a property comprises information about to which PDN connection eachof the radio bearers is mapped, and wherein the radio bearers compriseat least one radio bearer mapped to a first PDN connection and at leastone radio bearer mapped to a second PDN connection, wherein saiddetermining comprises determining that the at least one radio bearermapped to the first PDN connection should be handed over to the secondRAN.
 28. The method of claim 27, wherein the received informationcomprises IP addresses associated with each of the radio bearers, and/orthe linked bearer identification (LBI) associated with each of the radiobearers.
 29. The method of claim 24, wherein the information aboutmapping to a property comprises bearer IDs for each of the radiobearers, and wherein said determining comprises determining that atleast one of the radio bearers as identified by its bearer ID should behanded over to the second RAN.
 30. The method of claim 24, furthercomprising: receiving quality-of-service class indicator (QCI)information for each of the radio bearers, wherein said determining isalso based on said QCI information.
 31. The method of claim 30, whereinsaid determining comprises determining that bearers associated with aspecific QCI or range of QCIs can be handed over to the second RAN. 32.The method of claim 24, wherein the first RAN is a cellular RAN and thesecond RAN is a wireless local-area network (WLAN).
 33. The method ofclaim 32, wherein the information about mapping to a property isreceived from a CN node via a base station in the first RAN.
 34. Themethod of claim 24, wherein the first RAN is a WLAN and the second RANis a cellular RAN.
 35. The method of claim 34, wherein the informationabout the mapping is received from a trusted wireless access gateway(TWAG) associated with the WLAN.
 36. The method of claim 24, wherein thehandover command is configured to instruct the radio device to hand overat least one but fewer than all of the radio bearers of the radiodevice.
 37. The method of claim 24, wherein said handover commandcomprises a Radio Resource Control (RRC) Connection Reconfigurationmessage comprising one or more parameters used for the hand over.
 38. Amethod, performed in a base station of a cellular RAN, the methodcomprising: receiving information about a mapping to a property, of eachof a plurality of radio bearers of a radio device for carrying datatraffic between the radio device and the cellular RAN; and forwardingthe mapping information to an MF node for use in determining that atleast one of the radio bearers can be handed over to a WLAN RAN.
 39. Themethod of claim 38, wherein the mapping information is received from acore network node.
 40. A mobility function (MF) node for a communicationnetwork, the MF node comprising: a communication interface configuredfor communicating with one or more nodes of at least a first radioaccess network (RAN); processing circuitry; and a storage unit storinginstructions executable by said processing circuitry whereby said MFnode is operative to: receive information about a mapping to a property,of each of a plurality of radio bearers of a radio device for carryingdata traffic between the radio device and the first RAN; determine,based on the received information, that at least one of the radiobearers can be handed over to a second RAN; and initiate a handovercommand to the radio device instructing the radio device to handover theat least one radio bearer to the second RAN.
 41. A base station for acellular RAN, the base station comprising: a radio communicationinterface for communication with a radio device; processing circuitry;and a storage unit storing instructions executable by said processingcircuitry whereby said base station is operative to: receive informationabout a mapping to a property, of each of a plurality of radio bearersof the radio device for carrying data traffic between the radio deviceand the cellular RAN; and forward the mapping information to an MF nodefor use in determining that at least one of the radio bearers can behanded over to a WLAN RAN.